A number of games call for a playing surface upon which playing pieces are placed, rolled and/or moved in any number of manners. The rules of most such games require that the playing surface be level to some degree. For certain games (e.g., billiards and pool) in which playing pieces are particularly sensitive to how level the playing surface is, the requirement for a precisely leveled playing surface is very important to fair and proper game play. Achieving a high degree of precision for the level of a playing surface is a problem which is exacerbated by several variables. First, playing surfaces are often supported upon ground which itself is not level or which is unstable and which can change over time. Second, many playing surfaces are supported upon legs and/or a frame which by its construction or by its relationship to the playing surface may not support the playing surface in a highly level manner. For example, pool tables usually comprise a number of legs, a base frame secured and supported on top of the legs, slate (the playing surface) secured and supported on top of the base frame, and a number of rails secured and supported on top of the slate and/or the base frame to circumscribe the playing surface on the slate. The connection between the legs and the base frame and the base frame and the slate will inherently introduce some degree of imprecision into the level of the playing surface and increase the chances of an unsatisfactory playing surface. Similar results are found in other types of playing surfaces which are supported by multiple elements. Third, many playing surfaces themselves are not made from a single element. For example, pool tables often have a playing surface which is made from one, two, or three pieces of slate. Therefore, it is often necessary to level individual parts of the playing surface with respect to one another as well as with respect to the ground and the structure between the playing surface and the ground. Fourth, the playing surface and the structure supporting the playing surface will inevitably shift, sag, buckle, bow, or otherwise change over time. Such changes often result in undesirable modifications in the level of the playing surface. For example, the slate used for the playing surface of pool and billiards tables can slowly sag under its own weight (especially in lower-cost pool tables which employ thinner slate or thin slate backed and supported with wood). The causes of changes to a playing surface over time are typically a factor of material used, type and range of environmental conditions to which the playing surface and supporting structure are exposed, and the particular design, connection, and arrangement of the elements making up the playing surface and its supporting structure.
Many conventional systems and methods exist for leveling a playing surface in light of the variables just described. By way of example only, the following discussion regards the conventional systems and methods for leveling pool table surfaces. Such an example best facilitates insight into conventional playing surface leveling systems and methods because of the particularly exacting level standards required to play pool or billiards. However, it should be noted that other types of playing surfaces and the manner in which they are leveled are equally illustrative of the problems in conventional playing surface leveling technology. Therefore, it will be appreciated that the present invention is useful and finds application in solving leveling problems for all types of playing surfaces (including pool and billiards tables).
The conventional process of leveling a pool table is as follows. First, the legs and the base frame of the pool table are assembled and leveled upon the ground. The base frame can be leveled with respect to the legs by shims or by using a number of existing frame leveling devices well-known to those skilled in the art. After the leg and base frame assembly has been leveled, the pool table slate is placed upon the base frame. The slate can be one solid piece or can comprise two, three, or even more pieces which are typically placed in a side by side fashion on the base frame and are then secured in place to the base frame via conventional fasteners. The fasteners can be wood screws passed through apertures provided in the slate and into the base frame. The apertures in the slate are usually countersunk to permit the heads of the fasteners to rest therein without extending beyond the surface of the slate. Because the slates do not usually rest upon the base frame in a completely level fashion (due to inherent imperfections in the base frame, settling of the base frame under the weight of the slates, settling of the entire pool table and/or the supporting ground under the added weight of the slates, etc.), it is now necessary to level the slate pieces on top of the base frame. Typically, to accomplish this task, the fasteners are first loosened and shims are driven in appropriate places between the base frame and the underside of the slate pieces. These shims are usually made of pine, other types of wood, or other compressible or semi-compressible material. The shims compress slightly when the fasteners are once again tightened. Once the fasteners are tightened, the level of the slate pieces are checked and the level of each slate piece with respect to neighboring slate pieces is checked. If one or more pieces is not level, the process of fastener loosening, shim adjustment in appropriate places, and fastener tightening is repeated over and over again until the slate is completely level.
The conventional manner of playing surface leveling just described is unsatisfactory for a number of reasons. As can be expected from the description, the conventional process of leveling is very time consuming. Shims are particularly unsophisticated devices for making the frame adjustments required to perfectly level a playing surface. Not only are shims relatively difficult to adjust (by using a hammer and the right amount of hammering force upon the shims), but they are also subject to compression after their adjustment. Specifically, once the shims are hammered in place, the shims often compress as the fasteners tighten the slate to the base frame. This compression necessarily and undesirably changes the level of the slate. Therefore, the exact level resulting from proper shim adjustment and placement is typically a hit or miss proposition in which the user must crawl beneath the pool table, install, move, and/or shift shims, and then crawl from beneath the table to tighten the slate and check the resulting slate level. The repetition of this process is inefficient, cumbersome, and can be very frustrating, especially when one or more shims crack or break while the slate is being tightened (requiring the user to remove the broken shims and begin the leveling process over again).
Another problem with the conventional pool table leveling process described above is that shims used have a tendency to shift, crack, or even fall out of their locations over time. This occurs most commonly when the pool table is subjected to extreme or changing environmental conditions (e.g., a very dry room, repetitive swelling due to high or seasonal humidity, etc.). Unfortunately, these changes over time create the need for periodic re-leveling of the pool table.
Yet another problem with conventional pool table leveling systems and methods such as the one described above is a result of the location and arrangement of the fasteners and adjustment devices employed. Existing pool table leveling systems and methods rely upon fasteners to secure the slate pieces to the base frame and adjustment devices (shims) to adjust the level of the slate pieces in different locations around the slate pieces. The fact that the fastening locations are different than the adjustment locations causes undesirable stresses in the pool table slate pieces, especially during and after fastener tightening. Such stresses can cause the slate pieces to bow and even to crack. In cases where the pool table slate pieces are subject to a "memory" (i.e., where the slate pieces permanently deform when stressed or when stressed over prolonged periods of time), repeated adjustments to the pool table slates can result in permanently disfigured and ruined slates. Therefore, the practice of fastening a playing surface in a location which is different from the adjustment location of the playing surface is undesirable.
Therefore, a need exists for a playing surface leveling apparatus and method which permits a user to easily adjust the level of the playing surface at the same time as the playing surface level is monitored, allows for precise adjustment of the playing surface, does not employ elements susceptible to shifting or movement over time, uses an adjustment device which is readily accessible to a user (preferably from the top or sides of the playing surface) and easy to finely adjust, which does not subject the playing surface to undesirable stresses, and which preferably adjusts the playing surface in the same locations as it secures the playing surface to the underlying support structure. Each preferred embodiment of the present invention achieves one or more of these results.